1. Field of the Invention
This invention relates to an apparatus and method for exchanging an atmosphere of spherical object and more particularly to a spherical object conveying apparatus having a function of exchanging a conveying atmosphere when conveying spherical objects of spherical single crystal silicon, etc., through different atmospheres.
2. Description of the Related Art
Hitherto, normally, to form semiconductor devices, a method of forming a circuit pattern on a silicon wafer and dicing it as required for forming semiconductor chips has been adopted. In recent years, an art of forming a circuit pattern on a ball semiconductor of spherical single crystal silicon, etc., having a diameter of 1 mm or less and manufacturing semiconductor elements thereon has been developed.
For example, to use spherical single crystal silicon to form discrete devices of solar batteries, optical sensors, etc., or semiconductor integrated circuits, various treatment steps of a mirror surface grinding step of spherical single crystal silicon, a washing step, a thin film formation step, a resist application step, a photolithography step, an etching step, etc., are required. To efficiently manufacture the spherical semiconductor devices, the treatment steps need to be concatenated to form a line.
However, the treatment steps are executed in various atmospheres containing not only gases of active gases, inert gases, etc., but also liquids of water, solutions, etc. To concatenate such treatment steps, the treated substance transport atmosphere must not be brought into the following step from the preceding step. Thus, it is necessary to remove the atmosphere in the preceding step from the treated substance between steps and convert (exchange) into an atmosphere fitted to the following step. Moreover, to do this, high-speed treatment and high reliability are required from the points of productivity and quality.
When the treatment steps are concatenated to form a line, if spherical silicon conveyed from the preceding step is supplied to the following step irregularly, the supplied spherical silicon amount changes in the step. Thus, the treatment conditions must be changed in conformance with the change amount; efficient treatment cannot be executed.
Then, spherical objects of spherical silicon, etc., need to be supplied to the following step in sequence at given regular intervals. A silicon surface is easily oxidized and if a natural oxide film is formed on the surface, the contact property with a metal electrode layer, etc., formed on the surface (oxide film) worsens. It is desirable to convey and treat the spherical objects in a closed space without coming in contact with outer atmosphere.